What is Alagille syndrome?
Alagille syndrome is an inherited disorder that mimics other forms of prolonged liver disease seen in infants and young children. However, a group of unusual features in other organ systems distinguishes Alagille syndrome from other liver and bile duct diseases in infants.
Children with Alagille syndrome usually have a liver disease characterized by a progressive loss of the bile ducts within the liver over the first year of life and narrowing of bile ducts outside the liver. This leads to a buildup of bile in the liver, causing damage to liver cells. Scarring may occur and lead to cirrhosis in about 30 to 50 per cent of affected children.
What causes Alagille syndrome?
Alagille syndrome is generally inherited from only one parent and there is a 50 per cent chance that each child will develop the syndrome. Each affected adult or child may have all or only a few of the features of the syndrome. Frequently, a parent or brother or sister of the affected child will share the facial appearance, heart murmur or butterfly vertebrae but have a completely normal liver and bile duct.
What are the symptoms and physical characteristics of Alagille syndrome?
Symptoms of the illness are jaundice, pale, loose stools and poor growth within the first three months of life. Later, there is persistent jaundice, itching, fatty deposits in the skin and stunted growth and development during early childhood. Frequently the disease stabilizes between ages four and 10 with an improvement in symptoms.
Other features which help establish the diagnosis include; abnormalities in the cardiovascular system, the spinal column, the eye and the kidneys. Narrowing of the blood vessel connecting the heart to the lungs (pulmonary artery) leads to extra heart sounds but rarely to problems in heart function. The shape of the bones of the spinal column may look like the wings of a butterfly on x-ray but almost never cause any problems with the function of the nerves in the spinal cord.
More than 90 per cent of children with Alagille syndrome have an unusual abnormality of the eyes in which an extra, circular line on the surface of the eye can be detected by a specialized eye examination. However, it does not lead to any vision problems. In addition, some children have various abnormalities in their kidneys that may lead to minor changes in kidney function.
Many physicians believe that there is a specific facial appearance shared by most of the children with Alagille syndrome that makes them easily recognizable. The features include a prominent, broad forehead, deep-set eyes, a straight nose and a small pointed chin.
How is Alagille syndrome diagnosed?
Although Alagille syndrome was first described in English medical literature in 1975, it is now becoming recognized more frequently among children with chronic forms of liver disease. Diagnosis can be established by microscopic examination of liver biopsy specimens, a stethoscope examination of the child's heart and chest, a special eye examination (slit-lamp exam), an x-ray of the spinal column and an ultrasound examination of the abdomen.
How is Alagille syndrome treated?
Treatment of Alagille syndrome is primarily medical and not surgical and is based on trying to increase the flow of bile from the liver, maintain normal growth and development and prevent or correct any of the specific nutritional deficiencies that often develop. Because bile flow from the liver to the intestine is slow in Alagille syndrome, medications designed to increase the flow of bile are frequently prescribed. This may decrease the damage in the liver and improve the digestion of fat.
Itching caused by the buildup of bile in the blood and skin may be relieved by medication. Elevations in blood cholesterol also respond to the medications used to increase bile flow. Elevated blood cholesterol levels can lead to small yellow deposits of cholesterol on the skin of knees, elbows, palms, eyelids and other surfaces that are frequently rubbed. Lowering blood cholesterol usually causes the cholesterol skin deposits to improve.
Although reduced flow of bile into the intestine leads to poor digestion of dietary fat, a specific type of fat can still be well digested and therefore infant formulas containing high levels of medium-chain triglycerides (MCT) are usually substituted for conventional formulas. Some infants can grow adequately on breast milk if additional MCT oil is given. Foods containing fat may lead to looser, greasy stools later in childhood. However, the benefits from the calories and vitamins in the fat that is absorbed usually leads to the recommendation that the child not be put on a low-fat diet. There are no other dietary restrictions. Occasionally, MCT oil is also prescribed as a nutritional supplement.
Problems with fat digestion and absorption may lead to a deficiency of fat-soluble vitamins (A, D, E and K). Vitamin A deficiency causes night blindness and red eyes. Vitamin D deficiency causes softening and fractures of the bones and teeth. Vitamin E deficiency causes a disabling disease of the nervous system and muscles and vitamin K deficiency causes bleeding problems. Deficiencies of these vitamins can be diagnosed by blood tests and usually can be corrected by vitamin supplements.
Sometimes surgery is necessary during infancy to help establish the diagnosis of Alagille syndrome by direct examination of the bile duct system. However, surgical reconstruction of the bile duct system is not recommended because bile can still flow from the liver and there is presently no procedure that can correct the loss of the bile ducts within the liver. Occasionally liver cirrhosis advances to a stage where the liver fails to perform its functions. Liver transplantation is then considered.
The overall life expectancy for children with Alagille syndrome is unknown but depends on several factors: the severity of scarring in the liver, whether heart or lung problems develop because of the narrowing in the pulmonary artery and the presence of infections or other problems related to poor nutrition. Many adults with Alagille syndrome are leading normal lives.